Function ink_over 

pub fn ink_over(text: Hsla, page: Hsla, surface: Hsla, plate: Hsla) -> Hsla

The colour to draw text in over plate. surface is what text was coloured for: the opaque page with the washes under it, a highlight mark or a find match. plate is what is painted under it now, a selection or a solid caret over that surface. text where it reads there at the better of the contrasts it kept on the page and on the surface, else the surface’s own colour (inverse video) where that does, else whichever of black and white reads better.